OK, recent aquired a 93 xr250r. Starts and runs out pretty good. My concern is "White Smoke" very strong at idle once the bike is well warmed up. I am to old to be interested in Peak preformance, but if I need to get some top end work before thing deteriorate, where do I start.

So, should I suspect rings, maybe valves? might the just need an adjustment or could they be warn-out?
What would I spend for a complet top rebuild/ Do I need to include new cam and timing chain? Remember, the bike is running OK.

So, What say you? I'm not much of a mechanic but willing to get my hands dirty.

Thanks in advance for any help, suggestions, advise.

Welcome!

I just picked up an 88 for single track purpose,and love the little thing!

What i would do,if i were you,is first thing pull the plug and see what it says.
Is the smoke white,or blue?
White smoke would make me think its run'n lean.Everything else seems fine,like power,no weird noises,etc?
If it was blue smoke,i'd start with valve seals,was it sit'n for awhile?
I would start simple,and go up from there.So white smoke at start up,,,,,,read the plug and see if shes lean,open the air box and check the filter,if thats OK,then check your carb intake gaskets,and see if its got a leak and suck'n to much air.I've seen bikes do that because the air filter wasn't on right.Or some guys will do the free flow'n filters or cut the snorkle off,and open the air box up for more air,and not rejet,or not rejet properly.
Did the bike come from a lower elevation?Might be a jet'n issue.
If ya think its a ring problem,see if ya can do a compresion test,that'll tell ya if she need a set of rings.
A top end,if you do the work yourself shouldn't be that much money.And if it was me,and i had the top end off,i would do the cam,time'n chain,its a weak point and might save ya trouble down the road.
Dignostics,is the hardest part of mechanics!!!
But if it isn't your only bike,and ya got the time,start with the simple things and go from there.Beleave it or not alot of the time its something simple.
Keep us infromed,and we'll figure it out together.

__________________
"Hes not called the Angry White Man for nothing,much more fitting then the,Unicorn Clouds and Happy Trees Man".... UpST8